Proportioning scale



Oct; 20, 1953 Filed March 26, 1952 M. A. WECKERLY PROPORTIONING SCALE 3 Sheets-Sheet l Bnnentor MARK WECKERL) (Ittomegi Oct. 20, 1953 Filed March 26, 1952 W EJ M. A. WECKERLY 2,656,142

PROPORTIONING SCALE 5 SheetsSheet 2- Zinnentor 104 8g MARK A WECKERL Y W attorney Patented Oct. 20, 1953 PROPORTIONING SCALE Mark A. Weckerly, Toledo, Ohio, assignor to Toledo Scale Company, Toledo, Ohio, a corporation of New Jersey Application March 26, 1952, Serial No. 278,543

7 Claims.

This invention relates to weighing scales and in particular to a system of weighing scales for weighing out batches of material each batch being composed of several ingredients which enter into the batch in definite proportions accordin to weight.

It often happens in batching operations that the size of the batch may vary between wide limits whereas the proportions of the ingredients entering into the batch must be maintained within very close limits. An example of this condition is found in the mixing of concrete where the quantity of concrete required may vary widely according to the estimate of the job but where the proportions must be exact to maintain the quality of the product.

It also often happens that one ingredient for a mixture is a chunky material or one difiicult to feed in a steady controlled stream. If such a condition occurs the amounts of evenly easily ied an associated control suitable for automatically measuring out the ingredients for a batch wherein the weight of a first ingredient is employed as a counterbalance and the control mechanism automatically weighs out amounts of the other ingredients equal to fixed percentages by weight of f the first ingredient.

More specific objects and advantages are apparent from the following description of a preferred embodiment of the invention.

According to the invention a weighing scale system is provided with two or more load receivers arranged so that a first weighing scale indicator indicates the load in a first load receiver and a second weighing scale indicator indicates the condition of balance between the load in a second load receiver and the load in the first load receiver acting as a counterforce. Automatic controls are provided for sensing the condition of balance of the Weighing scale system and controlling feeding apparatus for feeding batch materials into the load receivers to bring the system into balance and maintain the system in balance.

In carrying out the invention the load receivers for a first and second commodity are, in effect, supported on the ends of a floating lever the fulcrum of which is supported by a first load counterbalancing and indicating mechanism. One end of the floating lever is also operatively connected to a second load counterbalancing mechanism which serves as an over-and-under indicator to indicate the condition of balance between the loads applied to the ends of the floating lever. In an actual weighing scale a force multiplying lever system is included between at least one of the load receivers and the floating lever and the multiplying lever system is made adjustable so that the proportionality between the weights of the batch ingredients may be varied.

Since the fulcrum pivot of a weighing scale lever is always subjected to a force that is proportional to the force being transmitted through the lever, the first load counterbalancing mechanism supporting the fulcrum of the floating lever indi cates the force being transmitted through the lever and thus may be employed to automatically control the weight of the batch being cornpounded.

A preierred embodiment of the invention is illustrated in the accompanying drawings.

In the drawings;

Figure I is a schematic elevation of a weighing scale system adapted to weigh out materials in a predetermined proportion for batches of various sizes.

Figure II is a schematic wiring diagram or the control mechanism for the feeders illustrated in Figure I.

Figure III is a diagrammatic representation or a lever system for compounding batches of three ingredients.

Figure IV is a schematic diagram illustrating the extension of the diagram of Figure II to include the control for the third feeder.

These specific figures and the accompanying description are intended merely to illustrat the invention but not to impose limitations on the claims.

A batching system constructed according to the invention comprises a first load receiver or hopper I which is pivotally supported by a link 2 from an end pivot 3 of a floating lever 3. The lever 4, of the first class, has a fulcrum pivot 5 supported from a steelyard rod 5 leading to a first weighing scale 1, The weighing scale 1 comprises a cabinet 8 housing a lever system which includes a pair of beams 9 and Iii carrying poises ll and 42 adapted to counterbalance loads applied through the steelyard rod 6. The weighing scale i also includes an automatic load counterbalancing mechanism which may be either a pendulum or a spring arranged to rotate and indicator l3 according to loads being counterbalanced. The indicator I3 cooperates with an annular chart i4 housed within a generally watchcase-shaped housing 5 to indicate the magnitude of the load counterbalanced by the automatic mechanism.

The indicator I3 is equipped with a permanent magnet i8 arranged to co-operate with mercury-magnetic switches I! and I8. The switches are located in positions such that the magnet operates the switch I! as the pointer approaches a zero indicium IQ of the chart I4 and operates the switch I8 when the indicator i3 reaches the zero indicium I9. v

The automatic load counterbalancing mechanism is arranged to rotate the indicator I3 from its full scale position toward zero as the load applied to the steelyard rod 6 increases. With no load in the hopper I and with the poises II and I2 located at th left ends of the beams S and I8 the mechanism is adjusted so that the pendulums are in their elevated position (or if a spring, so that the spring is extended) and the indicator I 3 stands at zero. To condition the scale for the production of a certain batch weight the poises II or I2 or both are moved to the right on the beams 9 and It), thereby decreasing the load applied to the automatic counterbalancing mechanism and causing the indicator to rotate clockwise to indicate on the chart Hi the decrease in load counterbalanced by the poises as a result of moving them to the right. As load is added to the hopper I the force through the steelyard rod increases, the pendulums rise, and the indicator returns toward its zero position. Actually the indication on the annuar chart I4 represents the amount by which the weight of the load in the load receiver or hopper I fails to equal the required load as predetermined by the positioning of the poises II and I2.

The mercury-magnetic switches I! and I8 through electric relays control a vibratory feeder 26 arranged to feed material from a supply bin 2! to the hopper or load receiver I.

A second ingredient for the batch to be produced is received in a second load receiver hopper 22 that is pivotally suspended from a knife edge 23 mounted in a carrier 24 that is slidable along a lever 25 iulcrumed on a pedestal 26. The lever 25 has a power pivot 21 pivotally engaged in a stirrup 28 on the bottom end of a steelyard rod 29 of a second weighing scale mechanism 39.

The weighing mechanism 38 comprises an automatic load counterbalancing mechanism enclosed within a dial housing 3I and arranged to drive an indicator 32 according to the load being counterbalanced. The scale mechanism also includes a pair of beams 33 and 34 on which are mounted poises 35 and 36 arranged to counterbalance or offset part of the load force transmitted through the steelyard rod 29. An adjustable stop 3? is arranged to limit the movement of the tip of the beams 33 and 34 at a point such that the indicator 32 cannot rotate counterclockwise substantially beyond its zero or balance position. When at the balanced or zero position, a permanent magnet 38 mounted on an arm 38 of the indicator 32 co-operates with a mercurymagnetic switch 40. As the load on the steelyard rod 29 decreases the indicator 32 is driven clockwise around the dial so as to indicate the amount of unbalance. As the indicator 32 rotates clockwise in response to decrease in load on the steelyard rod 29, the magnet 38 cooperates with a second mercury-magnetic switch 4I after leaving the first switch 40 and upon still further decrease in load leaves the second switch 4|. The switches 40 and 4| through relays control the flow of power to a vibratory feeder 42 arranged to feed material from a supply bin 43 to the second weigh hopper 22.

The lever 25 supporting the second weigh hopper 22 has still another pivot 44 engaging the lower end of a steelyard rod 45 the upper end of which is supported on a pivot 43 at the end of the floating lever 4.

In this arrangement forces from the load receiver I transmitted through the floating lever 4, fulcrumed on the steelyard rod 6, are transmitted through the steelyard rod 45 to the lever 25 to oilset loads applied to the hopper or load receiver 22. Thus while the load in the load receiver 22 tends to pull the steelyard rod 28 down and to rotate the indicator 32 counterclockwise, the force of load in the first load receiver or hopper I transmitted through the floating lever 4 urges the lever 25 upwardly in opposition to the load in the hopper 22 thus tending to drive the indicator 32 clockwise to indicate a deficiency of weight in the hopper 22.

The effective lever ratio of the hopper I with respect to the fulcrum pivot 5 is fixed by the distance between the pivots 3 and 5. The effective-lever ratio of the hopper 22 with respect to the fulcrum pivot 5 is determined by the position of the carrier 24 on the lever 25 and the distance from the pivot 46 of the lever 4 to the fulcrum pivot 5. In the arrangement shown wherein the lever i, as a first class lever, has a ratio of 3 to l a tension force of one unit in the steelyard rod 45 offsets 3 units in the hopper I. Likewise a tension force of one unit in the steelyard rod 45 offsets about 1 units in the hopper 22. Therefore, in the arrangement shown the system will be in balance with the indicator 32 indicating zero if the load in the hopper I is to the load in the hopper 22 as 3 /2 isto l /;,i.e.,7 to 3.

If it is desired to increase the quantity of material fed into the hopper 22 in proportion to the material fed into the hopper I the carrier 24 is moved along the lever 25 toward the fulcrum of that lever, which rests on the pedestal 26. Likewise if the proportion of the material fed into the hopper 22 per batch is to be decreased the carrier 24 and the suspended hopper 22 are moved (to the right in Figure I) toward the tip of the lever 25.

The feeder control mechanism for this system is arranged such that after the poises II and I2 have been set according to the desired batch weight, material is rapidly fed from the bin 2i through the feeder 26 into the hopper I. As material fiows into the hopper I, forces from the weight or" that material are transmitted through the steelyard. rod 6 to indicate the quantity of material and also through the steelyard rod 4-5 to the lever 25 and hopper 22 tending to raise the lever 25 thus driving the indicator 32 clockwise away from zero. [is this occurs the feeder 42 is energized by circuits controlled through the mercury-magnetic switches dd and 4| to initiate feeding or" material from the supply bin 43 across the second feeder 42 and into the second hopper 22. If during the time that material is fed into the hopper l the weight of material in the hopper 22 approaches or equals the predetermined percentage of the weight in the hopper I th indicator 32 approaches zero and by the co-operation with the switches H and 43 slows or stops the feeder 42 to prevent the accumulation of an excess of material in the hopper 22. As additional material flows into the hopper l the condition of balance is again upset and the second weighing mechanism 38 through the switches 46 and 4| re-energizes the feeder 62 to supply material to the hopper 22 thus tending to restore the condition of balance.

When the quantity of material in the hopper approaches the desired weight the indicator l3 of the scale I approaches zero and through its co-operation with the mercury-magnetic switches I! and I8 first slows down the action of the feeder 2e and then, as the indicator reaches zero, stops the feeder 20. If at this time the load in the second load receiver 22 is the correct percentage of the load in the receiver the in dicator 22 of the second scale 30 also stands at zero and the system is de-energized. If the load in the second receiver is too low the scale 30 is unbalanced and the feeder 42 continues to operate until the indicator 32 returns to zero.

Control circuits for carrying out this operation are illustrated in Figure II of the drawings. This operation may be followed by considering the wiring diagram, Figure II, in combination with the mechanical system shown in Figure I and assuming that both hoppers I and 22 are empty, that the poises H and i2 have been pos tioned to desired weight, and that the indicator l3 stands at a point on the chart it indicating the desired batch weight. Then, referring to Figure II, a start button so is manually depressed so that current may flow from a source of control power through a stop button a lead 52, and the now closed start button ac to a control power lead 53. From the lead 53 current flows to a branch lead 56, normally closed contacts 55 of a stop relay 56, an operating coil of a holding relay 58, and through a return lead 53 to a return control power lead 66. In response to this current flow the holding relay 58 closes its contacts 6| to complete a shunt circuit from the lead 52 through a lead 62, the now closed contacts El and a lead 63 through the lead 54 connected to the control power lead 53. This shunt circuit permits the start button 5!] to be released without tie-energizing the control lead 53.

As soon as the start button 59 was depressed and as long as the holding relay 58 maintains a shunt circuit or bypass around the start button 59 from the lead 52 to the control lead 53, a power relay M closes its contacts 55 so that power may flow from power lines 66 through the now closed contacts 65 to leads 6'! and 68' supplying power to the vibratory feeders 29 and 42. The feeders may or may not operate although the relay 64 is energized depending upon whether or not the loads on the weighing scales, acting through the mercury-magnetic switches call for operation of the feeders or not. Under the assumed conditions of no load in the hopper and the indicator l3 displaced from zero the mercury-magnetic switches l1 and I8 are both open. Furthermore, current may flow from the control power lead 53 through a lead 69, a normally closed contact If? of a final cutoff relay 1|, a lead 12, an operating coil of a vibrator control relay 13 and a return lead M connected to the return control power lead 5%]. Current flow through the operating coil of the vibrator control relay 13 causes it to close its contacts 15 so that current may flow from the power lead 68, through the now closed contacts 15 and a lead 16, through a normally closed contact ll of a first cutoff relay l8, and then through a lead 19 to a vibrator motor 86 of the vibrator feeder 20. From the vibrator motor 80 current returns through a lead 8| to the return power lead 61. Thus energized, the vibratory conveyor 20 feeds material into the hopper and the increase in weight thereof is indicated by the weighing scale indicator I3 rotating counterclockwise toward its zero load position. As it approaches its zero load position the magnet it reaches the first mercury-magnet switch ll and closes it so current may flow from the control power lead 53 to a branch lead 82, the now closed mercury-magnetic switch I! and a lead 83, through an operating coil 84 of the first cutoff relay l8, and through a lead 85 connected to the return control power lead 68. The relay is, thus energized, opens its normally closed contacts 71 and closes a first pair of normally open contacts 86 to complete a circuit from the control power lead 53 through the now closed contacts 86 to the lead 83 thus shunting the mercurymagnetic switch I! and sealing the relay F8 in its energized position.

The opening of the normally closed contacts IT as the first cutoff relay 18 is operated forces the vibrator motor current to flow through a resistor 81 connected in parallel with the contacts Tl so as to reduce the speed of the vibratory motor 80. Upon further increase in load, now occurring at a low speed, the indicator 3 continues its approach toward zero and as it reaches zero operates the second mercury-magnetic switch Hi to complete a circuit from the power lead 53 and branch lead 82 through the now closed switch i8, lead 88, now closed contacts 89 of the first cutoff relay 18, to an operating coil 90 of the final cutoff relay 1|. As the relay 1| operates it opens its normally closed contacts I0 to tie-energize the vibrator control relay 13 thus stop the vibrator motor 80 and at the same time closes its normally open contacts 9| to complete a circuit from the control power lead 53 through the now closed contacts 9! to electrically seal the final cutoff relay H in its energized condition.

This completes the cycle of operation for a batch in-so-far-as the hopper and weighing mechanism 1 for the first material are concerned and this condition is indicated by the relay H closing a pair of normally opened contacts 92 to energize a lead 93 leading to that portion of the control circuit relating to the second weighing scale mechanism 30.

At the start of the weighing operation and bcfore any material is fed into the hoppers the indicator 32 of the second weighing mechanism 3:: stands at zero so that the mercury-magnetic switch 40 was closed. As long as the switch 40 is closed current can flow from the power lead 53 through a lead 94, the now closed mercury-magnetic switch 40, a lead 95 and operating coil 93 of a slow-speed cutoff relay 9'! and a lead 93 connected to the return control power lead G0. As long as this circuit is complete the relay 9! holds its normally closed contacts 99 open and its normally open contacts I00 closed. As long as the contacts 99 are open no current can flow from the power lead 68 to the second vibratory feeder 42.

As load is added to the first hopper l and the weighing system becomes unbalanced the indicator 32 of the second scale leaves its zero position to close the other mercury-magnetic switch 4| and shortly thereafter open the first mercury-magnetic switch 40. As the switch 40 opens and die-energizes the relay 91, the normally closed contacts 39 are closed so that current may flow from the lead 68 to a lead IOI leading to contacts I22 of a fast speed control relay I03. The contacts I02 are open at this time because the indicator has moved so that its magnet 38 co-operates with the second mercury-magnetic switch 4| thereby completing a circuit from the energized lead 94 through the now closed switch 5!, lead I64, operating coil I05 of the relay I03, and a return lead I05. As long as the relay I03 is thus energized and the relay 9? is de-energized current may flow from the lead 58, through the contacts 99, through the lead IBI, a resistor I61, and a lead I03 connected to a vibrator motor I08 of the vibratory feeder 42. The vibrator motor m9 is also connected to the return power lead 6?. This current flow causes the motor we to operate at slow speed.

As the unbalance condition increases because of further rapid addition of load to the hopper I, the indicator 32 rotates still further in a clockwise direction so that the second mercury-magnetic switch 4! is opened thus breaking the circuit to the relay Iii-3 thereby closing the contacts I82 to complete a by-pass circuit through a lead I I0 around the resistor ID'I' so that full power is applied to the vibrator motor I99 and the vibratory feeder 52 operates at full speed.

For best operation the full feeding speed of the vibratory conveyor 42 is such that the hopper 22 is filled to its desired weight before the hopper I receives its full load. In other words material is fed to the hopper 22 at a rate more than sufiicient to maintain balance in the lever system. i=

As the load in the hopper 22 gains on the load in the hopper I the indicator 32 approaches zero and its magnet 38 co-operates with the second mercury-magnetic switch M to energize the relay IE3 and thus break the by-pass circuit around the resistor is"! so that the vibratory feeder 42 operates at slow speed. Actually the control fluctuates between its fast and slow speed condition as the load in the hopper 22 is maintained at slightly less than the desired percentage of the load in the hopper I. the load in the hopper 22 fails to match the load in the hopper I depends upon the force required to rotate the indicator 32 to a position where the mercury-magnetic switch M is just operated or just released.

After the first weighing mechanism has filled the hopper I to the desired weight and has energized the control lead 93 the current may flow from the lead 93 through a continuing lead III and contacts I I2 to the lead IN to hold the relay I83 closed. so that the vibratory feeder 22 can no longer be operated at high speed even though the mercury-magnetic switch 4| is opened.

Since the hopper I has received its load and its control is de-energized, its weight remains constant and the continuing dribble feed resulting from slow speed operation on the vibratory feeder 42 finally brings the weight of the second weigh hopper 22 to the point where the indicator 32 returns to its zero position and operates the first mercury-magnetic switch 48. This energizes the relay 9'! so as to break the contact 29 and thus stop the feeder 42. At this time both of the hoppers I and 22 have received their full loads and this is indicated in the control circuit by the completion of the circuit from the lead 93, which was energized when the hopper I reached its desired net weight, through the contacts I08, which were closed by the relay 91 when the sec- The amount by which 0nd hopper 22 reached its correct weight, to a lead I I3 connected to an operating coil I I4 of the stop relay 56 connected through lead II5 to the return lead 93. The relay 56 thereupon opens its contacts 55 thus interrupting the current flow to the relay 58 So that it releases its contacts ill to interrupt the flow of power to the control power lead 53 and thus de-energizes the complete system.

This completes the cycle of filling and the material in the hoppers I and 22 may be discharged into a common container or mixer with the assurance that the ingredients are in the correct proportion by weight. Since the final cutoff of the flow of material into the hopper 22 is determined by the condition of balance between the loads in the hoppers I and 22, any error in arriving at the correct weight in the hopper I does not affect the proportionality of the weights. Therefore if one of the materials is chunky or hard to feed it may be fed into the hopper I in such uantities as may be convenient and without particular attention to arriving at an exact weight. The easily fed material is fed through the feeder 42 to the hopper 22 where an accurate cutoff may be maintained to assure exact proportionality of the weights of the materials.

It occasionally happens that three or more ingredients are required in a batch and that these ingredients must be included in definite percentages according to weight even though the total hatch Weight may vary over a wide range. While the system previously described can readily proportionv two ingredients for a batch it cannot be user. for more than two. The principle of the system may be extended to a plurality of ingredients and in the extended system a first ingrediout, which may be the one that is difficult to feed, is employed as a counterbalance in a weighing system for Weighing out the second and other ingredients. A lever system suitable for three ingredients is illustrated in Figure III. In this system the first ingredient for a batch is fed into and collected in a first hopper I29 pivotally suspended at the end of a first arm I2I of a first floating lever I22. The floating lever I22, which is of the first class, is ful runied on a lower end of a steelyard rod I23 connected to a first weighing mechanism I24. This much of the system is identical to the hopper 5 and the weighing mechanism 'I illustrated in Figure I. A second arm I25 of the floating lever I22 is connected through a steelyard rod I25 to support the fulcrum of a second floating lever I2! also of the first class. A first arm I28 of the second floating lever I21 is pivotally connected through a steelyard rod i2 to a first second-class lever I39 which is fulcrumed on a pedestal ISI. The tip end of this second-class lever l-it' is cperatively connected to the second counterbalancing mechanism I32 which is adapted to indicate the condition of balance or the amount of unbalance of the secondclass lever I 36. A second load receiver or hopper I33 is pivotally suspended. from a carrier I235 slidably mounted on the first second-class lever I30. It will be noted that the second-class lever I36 and the counterbalancing mechanism I32 along with the load receiver I33 corresponds to the sec ond weighing mechanism 38 and hopper 22 illustrated in Figure I except that the arm I23 of the second floating lever I2? is included between the first second-class lever I39 and the first floating lever I22.

A second arm I of the second floating lever I2! is connected through a steelyard rod t second second-class lever I31 fulcrumed on a second pedestal I38. The tip of the second secondclass lever I31 is pivotally connected to and supported by a third load counterbalancing mechanism I39 adapted to indicate the direction and amount of unbalance of the forces applied to the second second-class lever I31. A third load receiver or hopper I40 is pivotally supported from a carrier I4I that is mounted for adjustment along the length of the second second-class lever I31. In this arrangement the magnitude of the load in the first hopper I20 is indicated on the dial of the first weighing mechanism I24. A force proportional to the weight in the first hopper I20 is transmitted through the floating lever I22 and the steelyard load I26 to the second floating lever I21 where it is divided and a part transmitted to the first second-class lever I30 and a part transmitted to the second second-class lever I31. The division of force between the two second-class levers depends upon the ratio of the second floating lever I21. The forces transmitted through the steelyard rods I29 and I36 from the second floating lever I21 act as counterforces to counterbalance the weight of material added to the hoppers I33 and I40. The condition of balance, 1. e. the loads in the hoppers I33 and I40 compared to the force transmitted through the steelyard rod, which is, in turn, proportional to the load in the first hopper I 20, is indicated by the weighing mechanisms I32 and I39.

The electrical control for automatically filling the hoppers operates in much the same manner as the control illustrated in Figures I and II. In

this control the first Weighing mechanism I24 operates as an ordinary batching control scale to fill the first hopper I20 to a weight selected by the counterbalancing portion of the first weighing mechanism I24. This control determines the size of the batch. Simultaneously, controls operated by the second and third counterbalancing mechanisms I32 and I39 feed material to the hoppers I33 and I40 and continuously maintain the weight in these hoppers generally in proportion to the weight in the hopper I20. Therefore the second and third hoppers I33 and I40 are loaded in amounts that are proportional to the load in the first hopper I20 regardless of the magnitude of that load.

Figure IV is a schematic wiring diagram to show the additional circuits required to replace a portion of the circuit illustrated in Figure II when the control is to operate with three scales and three ingredients. Since the control for the weighing mechanism I24 is the same as the control for the weighing mechanism of Figure I that portion of the diagram in Figure II appearing to the left side and including the leads 19 is not repeated in the diagram of Figure IV and Figure IV is to be considered as replacing the right half of Figure II with the leads indicated with prime reference numerals being connected to the correspondingly numbered but unprimed leads in Figure II leading from the left to the right portion of the diagram.

Referring now in particular to Figure IV and assuming that a weighing operation has been started and some material fed into the hopper I20, the lever system is unbalanced and the indicator of the second weighing mechanism, which co-operates with a pair of mercury-magnetic switches I50 and II moves away from zero to allow both switches to open. The co-operation,

of the indicator and the switch I5I is such that the switch I5I is closed when the weighing mechanism I32 indicates that the first second-class lever is in balance and is opened as soon as a change in balance occurs. The indicator also co-operates with the other switch I50 so that this switch is closed when the indicator stands near the zero or balanced position and for a short distance in the direction such that the load in the second hopper I33 is less than the desired amount. Since the load in the hopper I is increasing because of the operation of the circuit shown in Figure II the indicator of the weighing mechanism I 32 leaves its zero position and opens the mercury-magnetic switches I50 and I5I. Under this condition current may fiow from the vibrator motor supply lead 63 through a lead I52, normally closed contacts I53 of a final cutoff relay I54, through a lead I55, normally closed contacts I56 of a slow feed relay I51 and through a lead I53 to a vibrator motor I59 of a vibratory feeder I60 feeding material to the hopper I33. The return side of the vibrator motor I59 is connected to the power return lead 61'. Under this condition with both the switches I50 and I 5| open and the relay I 54 de-energized the vibratory feeder I60 operates at full speed to deliver material to the hopper I33. As the weight in the hopper approaches the correct value and the indicator of the weighing mechanism I 32 indicates this condition the indicator operates the first of the mercury-magnetic switches I50 to permit current to fiow from the energized control lead 34' through the switch I50, a lead IBI, and operating coil I62 of the relay I51, and a return lead I63 to the return control power lead The relay I51 opens its contacts I56 which are in parallel with a resistor I64 so that the current flow to the vibrator motor I is reduced and the vibratory feeder I Operates at slow speed.

Since the load in the first hopper I20 is still increasing, the slow speed of the feed to the hopper I33 is not enough to keep the weighing mechanism in approximate balance and as the unbalance increases, the magnet on the indicator releases the mercury-magnetic switch I50 thereby opening the circuit to the slow feed relay I51 which when released permits the vibratory feeder I60 to operate at full speed. This operation at fast and slow speed continues until the first weighing mechanism I24 indicates that the load in the hopper I20 has reached the correct value. When this occurs and the control for the first weighing scale I24 is de-energized a circuit is completed to the lead 93 of Figure II, the lead 93' of Figure IV, so that the next time the switch I50 is operated as the first second-class lever I 30 approaches balance and the relay I51 is energized current flows from the lead 93' through the normally open contacts I of the relay I51 to complete a circuit in parallel with the mercurymagnetic switch I50 and thus electrically seal the relay I51 in its energized condition. Thi prevents the control mechanism for the feeder I60 returning to high speed operation should the mercury-magnetic switch I50 be opened.

As the slow speed feed of material to the hopper I33 brings its weight to the desired value the indicator of the weighing mechanism I32 operates the second mercury-magnetic switch I5I o that current may flow from the energized control lead 94 through the now closed mercury-magnetic switch I5I, lead I66, and operating coil I61 of the final cutoff relay I54 to the return control power lead 98. Thus energized the cutoff relay I54 opens its contacts I53 thus stopping the action of the vibratory feeder I60 and at the 11 same time indicating this condition by closing its contacts H58 so current may flow from the signal lead 83' through the contacts I68 to energize a continuing signal lead I 69.

The third counterbalancing mechanism i33, which is operatively connected to the second second-class lever is! supporting the third hopper M0, is equipped with first and second mercury-magnetic switches ill! and I'll. These switches co-operate with relays to operate a vibratory feeder IBM to feed material into the hopper I40. Inasmuch as these circuits are identical in structure and operation with the circuits co-operating with the weighing mechanism I32 the description of that circuit will not be repeated but the description may be applied to the circuits of the weighing mechanism 139 by replacing each of the reference numerals with the same reference number followed with an a.

There is one portion which must be separately considered and that is the connection of the signal lead I69 through contacts I580; the final cutoff relay E ia to the signal lead i 13 when the controls indicate that the second second-class lever I3? is in balance following the addition of weight to all of the hoppers.

As will be recalled from Figure II, as soon as the signal lead 93 is connected through to the lead H3 current flows through the relay 56 to break the circuit of the sealing relay 58 and thus de-energize the entire system.

The application of this system of proportioning batch materials by using the weight of one material as a counterforce may be extended indefinitely by following the same method of extension as was used in extending the lever system shown in Figure I to the system shown in Figure III and including control circuits for each similar to the control circuit shown in Figure II and its extension as shown in Figure IV.

Various modifications of the structure and circuit may be made without departing from the scope of the invention.

Having described the invention, I claim:

1. In a device of the class described, in combination, a load receiver, a lever system serving to support the load receiver, a first and a second load counterbalancing mechanism each operatively connected to the lever system, a second load receiver, a lever that connects the second load receiver to the second load counterbalancing mechanism and that transmits to the first counterbalancing mechanism a selectable fraction of the load force of the second load receiver in opposition to the force transmitted to the sec ond counterbalancing mechanism by load in the first load receiver, feeders for feeding material into said load receivers, and a control system that is responsive to the counterbalancing mechanisms for controlling the feeders.

2. In a device of the class described, in combination, a load receiver, a lever system serving to support the load receiver, a first and a second load counterbalancing mechanism each connected to the lever system to jointly counterbalance the load in said receiver, a second load receiver, a variable ratio lever system for connecting the second load receiver to the second counterbalancing mechanism to oifset the load force from the first load receiver, a feeder for each load receiver, a control system including the first load counterbalancing mechanism for operating the first feeder for feeding material into the receiver until a selected weight is reached, and a control system including the second load counterbalancing mechanism for operating the second feeder to maintain a sufncient quantity of material in the second load receiver to offset the load force of the first receiver applied to the second counterbalancing mechanism, whereby the loads in the receivers are maintained at a predetermined ratio of weight at the time of final weighing.

3. In a device of the class described, in combination, a load receiver, a lever system serving to support the load receiver, a plurality of load counterbalancing mechanisms each connected to the lever system to counterbalance a predetermined part of the load, other load receivers, a variable ratio lever system for connecting the other load receivers to certain of the counterbalancing mechanisms for applying the load forces of said other receivers to the counterbalancing mechanism in opposition to the force of the first load receiver, a plurality of mercurymagnetic switches mounted in the counterbalancing mechanisms, a feeder for each load receiver for feeding material thereto, and circuit means responsive to the mercury-magnetic switches for controlling the feeders.

4. In a device of the class described, in combination, a first load receiver, a lever system serving to support the load receiver, at least two load counter-balancing mechanisms operatively connected to the lever system, at least one other load receiver, a lever system for transmitting load forces from each of said other load receivers to a corresponding one of said load counterbalancing mechanisms to apply force in opposition to the force transmitted from the first load receiver, control means sensitive to the condition of balance of each load counterbalancing mechanism, and a feeder for each load receiver, each feeder being under the control of the control means associated with the corresponding load counterbalancing mechanism.

5. In a device of the class described, in combi nation, a first load receiver, a lever system that supports the load receiver, a plurality of load counterbalancing mechanism operatively connected to said lever system, a. second load receiver, a lever system for supporting the load receiver and transmitting load force to one of the load counterbalancing mechanisms in opposition to force from the first load receiver, a feeder for each load receiver, and a control system for each feeder, the control system for the first load receiver serving to stop the feeding of material when a predetermined quantity of material has accumulated in the first receiver, the control system for the feeder for the second load receiver serving to feed material as long as that load counterbalancing mechanism indicates a lack of balance between the weights in the receivers 6. In a device of the class described, in combination, a first load receiver, a lever system that supports the load receiver, a plurality of load counterbalancing mechanisms operatively connected to the lever system, a plurality of other load receivers there being one load receiver for each load counterbalancing mechanism, a plurality of lever systems, one for each of the other load receivers, said lever systems being connected to the load counterbalancing mechanisms in opposition to the lever system supporting the first load receiver, a feeder for feeding material to each load receiver, a control system for each feeder, each control system including a portion sensitive to unbalance of the associated load counterbalancing mechanism and being adapted 13 to feed material whenever an unbalance occurs, an electrical contact in each control system that is closed when there is no unbalance, and a circuit including said contacts for de-energizing all the control systems when they simultaneously indicate a balanced condition.

7. In a device of the class described, in combination, a first load receiver, a lever system that supports the first load receiver, a load counterbalancing mechanism operatively attached to the lever system, a plurality of other load receivers, a plurality of lever combinations for supporting each of the other load receivers respectively, a force transmitting connection from each of the lever combinations to the lever system whereby the load in the first load receiver serves as a counterbalance for loads in the other receivers, balance indicators connected respectively to each lever combination, and control means responsive to said force balance indicators for feeding material to the other load receivers.

MARK A. WECKERLY.

References Cited in the file of this patent UNITED STATES PATENTS 

